The Internet is a worldwide, publicly accessible network of interconnected computer networks that transmit data by packet switching using the standard Internet Protocol (IP). The Internet protocols comprise a suite of communication protocols, of which the two best known are the Transmission Control Protocol (TCP) and the Internet Protocol (IP).
In packet-switched networks such as the Internet, a router is a device or, in some cases, software in a computer, that determines the next network point to which a packet should be forwarded toward its destination. A router can be located at any gateway (where one network meets another), including each point-of-presence on the Internet. Routers within the Internet are organized hierarchically. Routers used for information exchange within autonomous systems are called interior routers, which use a variety of Interior Gateway Protocols (IGPs) to accomplish this purpose.
Internet Protocol (IP) routing protocols distribute information between routers and gateways. Whenever other functions in the network rely on distribution of certain information among network nodes, it is convenient to use transport mechanisms of routing protocols. Therefore, there are many examples of the transport mechanism of routing protocols is used for information distribution.
One of the examples is the usage of interior gateway protocols in the Generalized Multi-Protocol Label Switching (GMPLS) protocol family. See, for example, the Open Shortest Path (OSPF) protocol described in RFC2328 “OSPF Version 2”, J. Moy April 1998 (incorporated herein by reference); the Intermediate System to Intermediate System [IS-IS] protocol described, e.g., in RFC1142 “OSI IS-IS Intra-domain Routing Protocol” D. Oran, Ed. February 1990) (incorporated herein by reference).
In Generalized Multi-Protocol Label Switching (GMPLS) protocols, IGP protocols distribute information about physical fibers, WDM wavelength, and TDM channels as link state information. IGP protocols are described, e.g., in RFC4203 “OSPF Extensions in Support of Generalized Multi-Protocol Label Switching (GMPLS)”; K. Kompella, Ed., Y. Rekhter, Ed. October 2005 (incorporated herein by reference); and RFC4205 “Intermediate System to Intermediate System (IS-IS) Extensions in Support of Generalized Multi-Protocol Label Switching (GMPLS)”, K. Kompella, Ed., Y. Rekhter, Ed. October 2005 (incorporated herein by reference).
Besides connectivity information (link ID, link type, IP address), traffic engineering (TE) information is also distributed to support traffic engineering algorithms in the Path Computation Entity (PCE). IGP extensions for GMPLS rely on traffic engineering extensions of IGP protocols (see, e.g., RFC2370 “The OSPF Opaque LSA Option”, R. Coltun July 1998; RFC3630 “Traffic Engineering (TE) Extensions to OSPF Version 2”, D. Katz, K. Kompella, D. Yeung September 2003; RFC3784 “Intermediate System to Intermediate System (IS-IS) Extensions for Traffic Engineering (TE)”, H. Smit, T. Li June 2004, all of which are incorporated herein by reference. For more information on OSPF-TE and OSPF extensions for GMPLS, see RFC3630 and RFC4203, respectively, which are already incorporated herein by reference.
Besides the extension of link definition, there are many Internet Drafts that propose to extend IGP protocols so that they also advertise node capability information. In GMPLS, one such protocol is “IGP extension for PCE discovery” where PCE servers advertise their configuration information (including location and control capability info) and congestion state information in order to allow PCE clients to select the optimal PCE server. See, e.g., draft-ietf-pce-disco-proto-igp-02 “IGP protocol extensions for Path Computation Element (PCE) Discovery,” Jean-Louis Le Roux, pce, 27 Jun. 2006, (incorporated herein by reference). In addition to the PCE discovery IETF draft, there are further drafts discussing the advertising of node capabilities with IGPs. See, for example, draft-ietf-ospf-cap-08 “Extensions to OSPF for Advertising Optional Router Capabilities,” AceeLindem, ospf, 2 Dec. 2005 (incorporated herein by reference); and draft-ietf-isis-caps-06 “IS-IS Extensions for Advertising Router Information,” J P Vasseur, isis, 5 Jan. 2006 (incorporated herein by reference).
Exterior Gateway Protocol (EGP) routing protocols are also used for conveying non-IP-level information. Border Gateway Protocol (BGP) extensions are used to exchange connectivity information between different sites of a Virtual Private Network (VPN).
The above described usages of routing protocols to distribute non-IP level information shows that their application as a server configuration/status advertisement protocol is also feasible.
The system architecture of future mobile networks (referred to as System Architecture Evolution, or “SAE/LTE”) is being worked out in the standardization body known as the Third Generation Partnership Project (3GPP). The central node of System Architecture Evolution (SAE) is the Access & Core Gateway (ACGW), which could have physically separated user and control plane (i.e. split-architecture). In the split architecture, two entities are defined: (1) The Mobility Management Entity (MME) handles control plane (CP) signaling and it is responsible for mobility; and (2) the User Plane Entity (UPE) is the gateway for the user plane (UE) traffic). FIG. 1 shows a split architecture logical view of an example system.
A pooling concept is also discussed in System Architecture Evolution/Long Term Evolution (SAE/LTE) for Mobility Management Entities (MMEs) and User Plane Entities (UPEs), in order to reduce capacity, to increase reliability, and to allow for simplified planning. Mobility Management Entity (MME) pooling is a mechanism by which a base station node (e.g., NodeB) can handle multiple Mobility Management Entities (MMEs) as if they were a single logical entity. When a user requests a service, a mechanism selects one of the physical MME nodes and binds the user to the selected MME.
A similar pooling concept can also be defined for user plane nodes. In the case of user plane pooling, multiple UPE nodes are able to serve user sessions in a given region. It is the task of the MME (or other control plane entity) to select a given UPE from the pool when a user attaches to the network. Accordingly, users (and Base stations) do not see a difference between UPEs within the same pool.
Pooling is also used in earlier mobile systems (e.g., Iu-flex for Serving GPRS support Node (SGSN) pooling). See, e.g., 3GPP TS 23.236 “Intra-domain connection of Radio Access Network (RAN) nodes to multiple Core Network (CN) nodes, v 5.4.0; and v 6.3.0 which is incorporated herein by reference.
In operational networks, pooling configuration and gateway selection (in the SAE context MME and UPE selection) is based on statically preconfigured information. That is, intelligent UPE selection involves considerable configuration in MMEs (pool membership, server loads, transport info, supported services, node capacities) that needs to be aligned with the configuration of Base stations and UPEs. Therefore, it is likely that UPE selection will not consider part of this information.
Static pooling configuration makes configuration management of pools more cumbersome. For example, in a scenario where less expensive (and thus less reliable and smaller) User Plane Entities (UPEs) are used, network redundancy provided by pooling would allow for high network reliability. In this scenario, however, adding and removing UPEs (dynamically) to/from pools may become a frequent event, affecting configuration significantly.